First-floor extensions in Portlethen

Portlethen: the key facts for this kind of project.

Postcode districts: AB12
County / area: Aberdeen and Aberdeenshire, Scotland
Price region: Scotland
Guide price: £23,500–£34,000 (£1,690–£2,440 per m²)
Approval route: Planning permission is usually needed: Class 1B permitted development only applies if every part of the extension is at least 10 m from all boundaries. A building warrant is needed before work starts.
Nearest towns: Cove (2.8 miles), Nigg (3.6 miles), Aberdeen (5.3 miles)
Distance to Aberdeen: about 5.3 miles
First visit: Free, no obligation

About a first-floor extension

A first-floor extension is a new upstairs room built on top of an existing single-storey part of your house, such as a rear kitchen extension, a utility or a side annexe. It adds a bedroom, bathroom or study without enlarging the footprint. Whether it works depends mainly on whether the walls and foundations below can carry the extra load.

We cover Portlethen (AB12) and the places around it, including Cove (2.8 miles), Nigg (3.6 miles) and Aberdeen.

What it costs in Portlethen

Most of the cost of a first-floor extension is set by its size and specification. For Portlethen and the rest of Scotland, our guide is £1,690–£2,440 per m² including VAT, so about £23,500–£34,000 for 4 m × 3.5 m of new first-floor space (14 m²). We'll give you a written design-stage price first, then a fixed build price once the drawings are agreed.

Spec	Per m²	4 m × 3.5 m of new first-floor space (14 m²)
Essential	£1,560–£2,250 per m²	£22,000–£31,500
Standard	£1,690–£2,440 per m²	£23,500–£34,000
Premium	£2,030–£2,930 per m²	£28,500–£41,000

Planning and building standards in Portlethen

In Scotland, permitted development for extensions of more than one storey (Class 1B) needs at least 10 m to every boundary and no part higher than the house. Most first-floor extensions cannot meet the 10 m test, so plan for a householder application (£371, decided within two months) and a building warrant before work starts.

Approval in Scotland: Householder planning application: £371. Councils have two months to decide a local planning application.

Building standards: A building warrant from the council's building standards service before work starts, and a completion certificate at the end. Scotland uses its own Technical Handbooks.

Design points for Portlethen homes

Can the existing structure take it?

Many single-storey extensions were built with foundations, walls and lintels sized for one storey. We find out what is there with trial holes and, where available, the original building standards drawings. The engineer then decides whether to reuse, strengthen or rebuild parts of the structure.

Escape and fire safety

A new first-floor bedroom needs an escape window with a clear opening of at least 0.33 m², at least 450 mm wide and 450 mm high, with the bottom no more than 1,100 mm above the floor, unless there is a protected route to the stairs.

How we'd run your project

Understand the brief
At your home in Portlethen we agree what you need: bedroom count, bathroom, kitchen space, and how much garden you want to keep.
Design and approvals
We draw the extension and check it against the rules for Scotland, then apply for planning permission or a certificate of lawfulness, whichever fits.
Structure and building standards
A structural engineer sizes the foundations and steels, and we get a building warrant before work starts.
Finish and certify
Second fix, plastering and making good, then the council's final building standards inspection and the completion paperwork.

Questions about first-floor extensions in Portlethen

How long does a first-floor extension take?

Allow 4 to 8 weeks for survey and design, then the approval period (councils have two months to decide a local planning application), then 4 to 8 weeks of technical design, which can overlap. The build itself usually takes 14 to 20 weeks, longer for large or complex designs.

Which postcodes do you cover around Portlethen?

We cover Portlethen (AB12) and nearby places including Cove, Nigg and Aberdeen, plus the rest of Aberdeen and Aberdeenshire. The first site visit is free.

Do I need planning permission for a first-floor extension in Portlethen?

Portlethen is in Scotland. Planning permission is usually needed: Class 1B permitted development only applies if every part of the extension is at least 10 m from all boundaries. A building warrant is needed before work starts.

What happens to the room below while the first floor is built?

The old roof is removed, so the room below is exposed for a short period. We fit temporary weather protection, plan the work so the roof comes off only when the new structure is ready, and agree with you which rooms will be out of use and for roughly how long.

Can I build on top of my existing single-storey extension?

Often yes, but only after the structure has been checked. Foundations, walls and lintels built for one storey may not carry two. We dig trial holes, look for the original a building warrant and ask the structural engineer to confirm what can stay, what needs strengthening and what must be rebuilt.

Nearby

We also cover places near Portlethen, including:

Other extensions in Portlethen

All two-storey extension services in Portlethen · First-floor extensions across Aberdeen and Aberdeenshire

Ready to talk it through? Call us or send the form and we'll arrange a visit to your home in Portlethen.